Anchoring devices for well tools



Dec. 2, 1958 J. H. BOSTOCK ANCHORING DEVICES FOR WELL TOOLS Filed Feb;21, 1955 6;, 3 IN VEN TOR BY fl w ,4 Tram/5v United States PatentANCHORING DEVICES FOR WELL TOOLS James H. Bostock, Dallas, Tern,assignor to Otis Engineering Corporation, Dallas, Tex., a corporation ofTexas Application February 21, 1955, Serial No. 489,391 9 Claims. (Cl.166- 214) This invention relates to improvements in anchoring devicesfor well tools, and refers more particularly to such anchoring devicesespecially adapted for securing a plurality of'tools within a string. ofwell pipe at pre-selected levels therein and in such manner that thetools may be withdrawn from the well pipe.

In the production and drilling of petroleum wells and similar wells, itis frequently desirable to position one or more well flow controldevices within a string of pipe with such tool or tools anchored atselected levels in the pipe. The tools or flow controls may frequentlyrequire withdrawal from the well for repair or replacement or to permitaccess therepast to a lower level in the well topermit performance ofother operations on the well.

It is also desirable that the means for anchoring the flow controls orother well tools in place in the well pipe provide little or norestriction or reduction in the bore of the well pipe, so that accessmay be readily had to the bottom of the well or to the lower end of thewell pipe.

It is, therefore, one object of this invention to provide improvedanchoring devices and assemblies for securing tools in and releasingtools from a well pipe.

Another object of the invention is to provide anchoring devices andassemblies for securing well tools at predetermined levels in a wellpipe, which anchoring devices and assemblies are so constructed that anaccumulation.

of sand or other debris will not prevent withdrawal of the tool from thewell when desired.

It is a particular object of the invention to provide an anchoringassembly providing for positively positioning the anchoring device andthe well tool carried thereby at the selected one of several possiblelocations within the well pipe.

, Another object of the invention is to provide an anchoring" assemblyhaving separate lockingdogs and selector keys, the selector keysproviding means for selecting a predetermined position in a well pipeand preventing downward movement of the locking tool or anchoring toolin the pipe past such position.

A further object of the invention is to provide an anchoring assemblyhaving selective positioning and anchon'ng means thereon which areinterchangeable on the anchoring device, whereby the anchoringdevice maybe anchored in any one of several selected positions by'selection of theproper selective positioning and anchoring means.

A still further object of the invention is to provide an anchoringdevice and assembly of the character described which is readilyinsertable into and removable from the well pipe on a flexible lineraising and-lowering mechanism.

' Additional objects and advantages of the invention will be readilyapparent from the reading of the following description of a deviceconstructed in accordance with the invention, and reference to theaccompanying drawings thereof, wherein:

Figure 1 is a view partly in elevation and partly in section of a stringof well pipe having a plurality of landing sections made up therein inaccordance with the invention,

Figure 2 is an enlarged view, partly 1n elevation and partly in sectionof the locking and sealing portion of a.

Figure 4 is a horizontal cross-sectional view taken on.

the line 44 of Figure 3, and,

Figure 5 is a fragmentary sectional view showing the selector keys ofthe anchoring device passing through the selector groove section ofanother landing section.

In the drawings, Figure 1, there is shown a string of well pipe, whichmay be a string of flow tubing for conducting well fluids from aproducing formation of a well to the ground surface. This string of pipeis made up of a plurality of lengths of tubing 10, only small portionsof which have been shown, but which constitute a major portion of thelength of the string of well pipe. A plurality of landing sections, 11,111 and 211', are made up in the string of well pipe and constitute aportion thereof, said landing sections being connected to the tubing inthe usual manner by couplings 12', whereby the assembly constitutes aflow passage from the lower portion of the Well to the surface of theearth.

The landing sections are shown as each having a threaded pin 13 at itsupper end'and a similarly threaded.

pin 14 at its lower end by means of which said landing section isconnected in the string of well pipe. The bore 15 of the landing sectionis preferably of substantially the same internal diameter as the bore ofthe tubing'10 of trated, includes an internal annular locking groove 20,

an internal annular stop groove 21, and an upper selector groove 22 anda lower selector groove 23, said stop groove and selector grooves beingconsidered to be a portion of the same groove assembly.

The locking groove 20 preferably is formed with divergently inwardlyinclined shoulders 24' and 25 at its upper and lower ends, respectively,and is the groove in which the locking means of the anchoring device isto be secured, as will hereinafter be more fully explained. This groovefunctions principally as a part of the means for securing the anchoring.device against upward movement within the well pipe.

The grooves 21, 22 and 23 constitute the selective po the upper groovehas an upwardly and inwardly inclined shoulder 28 at its upper end and adownwardly and in-' wardly inclined shoulder 29 at its lower end, whilethe lower selector groove 23 has an upwardly and inwardly inclinedshoulder 30 at its upper end and a downwardly and inwardly inclinedshoulder 31 at its lower end. The tapered inclined shoulders of the stopgroove and of the selector grooves are provided for the purpose. offacilitating withdrawal of the anchoring device from the landingsection, since these inclined shoulders will cam or force inwardly anydog or key which might strike theshoulders, as long as there is nothingholding the dog or key ex- Patented Dec. 2, 1958 panded or preventingits retraction. The stop shoulder 26, however, is intentionally designedto arrest downward travel of the anchoring device when the selector orstop means of the anchoring device enters the stop groove 21. Thus,thefstop shoulder 26 functions to prevent downward movement of theanchoring device at any time that the selector or stop means on theanchoring device is positioned in the stop groove.

By reference to the several landing sections 11, 111 and 211,illustrated in Figure 1, it will be seen that the stop groove 21 and theselector grooves 22 and 23 in each of the various landing sections areof difierent diametrical dimensions, and that the diameter of thegrooves in the lowermost landing section is greater than the diameter ofthe corresponding grooves in the upper landing sections. It will also beseen that the grooves of each of the landing sections are larger indiameter than the diameter of the corresponding grooves in the landingsections thereabove. Thus, an anchoring device equipped with selectormeans which will fit into the stop groove of the lowermost landingsection will pass by the selector and stop grooves of each of the uppersections. Therefore, these stop grooves and selector grooves may beconsidered as selector key grooves.

Preferably, the exterior of the landing section each carries someindicia to indicate the size of the key grooves in order to facilitateassembling the landing sections in the string of well pipe with eachlanding section in its proper relative position in the pipe string. Forexample, the lowermost landing sectionhas a single exterior groove 32 inits periphery. The landing section next above has a pair of externalannular grooves 33 in its periphery, and the highest landing section hasthree external annular grooves 34 in its periphery. Obviously, thesegrooves indicate the proper relative position of each of the landingsections in the pipe string and, of course, the number of landingsections and the number of grooves may be correspondingly increased, orif desired a smaller number or a single landing section may be used inthe Well pipe.

It will be seen that the landing sections may be incorporated into thewell pipe string at any desired depth; and, if desired, one or more maybe incorporated as an integral portion of the well head equipment, orconnected directly thereto.

The anchoring devices used in connection with the landing sections areillustrated in Figures 2 through 5, and in the form shown may beconsidered as comprising -a three part carrier 35 made up of a neckmember 36 and expander and connector member 37 and a packing and keyholder member 38. The carrier may have a flow passage 39 therethrough. Acarrier sleeve 40 is slidably mounted on the neck member 36 and carriesat least one locking dog 41 in a manner to permit expansion andretraction of the locking boss 42 at the lower end of the dog. Aplurality of dogs are shown and are the preferable construction. Thelower portion of each locking dog is slidable upon the frusto-conicalexpander surface 43 of the expander and connector member 37 betweenexpanded and retracted positions, and when expanded is adapted to engagein the locking groove 20 to hold the carrier 35 against upward movementout of the landing section. The carrier sleeve 40 is shown as havlng anenlarged lower skirt portion provided with an internal counter-bore witha shoulder 43 formed therein on which the locking dog 41 is swingablymounted by an outwardly projecting lug 44 formed at the upper end of thedog and resting on the shoulder 43. A clearance is provided between theinner side of the dog and the perrphery of the neck 36, whereby the dogis' free to rock inwardly and outwardly upon the outwardly extending lug44 resting on the shoulder 43. Longitudinal upward movement of thelocking dogs and the carrier sleeve 40 is limited by an enlargement orhead 45 at the upper end of the neck portion 36 of the carrier, theupper end of the carrier sleeve engaging the lower end of saidenexpander surface 43, from an upper retracted position to a lowerexpanded position. Downward movement of the dogs on the expander surfaceis limited by an up wardly facing stop shoulder 47 at the lower end ofthe expander surface, which engages the lower end of the dogs and limitsfurther downward movement of the dogs on the expander member. Thus, withthe dogs expanded into the locking groove 20, the engagement of theupper end of the boss 42 on the dogs with the downwardly facing lockshoulder 24 in the locking groove, together with the engagement of thelower end of the dogs with the shoulder 47 on the expander member willprevent upward movement of the carrier out of the landing section.

While a plurality of dogs have been'shown as incorporated in theanchoring device, it is believed obvious that one or more dogs,preferably not more than four, may be used. Also, while the relativemovement between the expander member and the dogs has been shown as anupward movement of the expander with respect to the dogs, it is believedobvious that any other suitable longitudinal movement between anexpander member and a locking dog which will hold the boss of the dog inexpanded posi tion in the locking groove may be utilized for the purposeof anchoring the anchoring device in the landing section.

Sealing means, shown as being in the form of a plurality of invertedV-shaped packingrings 50 is mounted on the packing and key holder member38 below the expander and coupling member 37, the packing being confinedbetween an upwardly facing shoulder 51 on the packing and key holdermember and the lower end 52 of the expander and coupling member. Thepacking rings are adapted to engage and seal against the bore wall 15 ofthe landing section 11 to prevent upward flow of fluid exteriorly of thecarrier through the landing section.

For inserting the anchoring device into the well pipe, at suitablerunning tool R having a socket in its lower end is engaged over theenlarged head 45 of the neck member 36, in the manner shown in Figure2,. and is detachably secured thereto by one or more shear pins 55extending through the opposed transverse apertures in the running tooland engaging in substantially tangential grooves 56 formed on theopposite sides of the enlarged head of the neck member. The running toolmay be connected to any suitable flexible line raising and loweringmechanism (not shown) in the manner well known to those skilled in theart, whereby the anchoring device may be lowered into, manipulated in,and removed from the well pipe by means of such raising and loweringmechanism.

When the tool has been lowered into the well pipe and engaged in properlanding section, the running tool R may be disconnected therefrom byupward jars or force applied to the running tool, which will shear therivets or pins 55 and permit the runningtool to be withdrawn from thewell bore;

To withdraw the anchoring device from locked position in the well pipe,a retrieving or fishing tool or the like is lowered into the well pipeby the flexible line lowering mechanism and engaged with the enlargedundercut flange 46 on the upper end of the carrier sleeve 40. Theretrieving tool has a part that first strikes the head 45 ofthe neckmember to drive the same downwardly and move the expander surface 43downwardly with respect to the locking dogs 41, whereby the dogs arefree to retract inwardly when the bosses thereon engage the beveledshoulder 24 at the upper end of the locking groove 20, or any otherprojection or shoulder. in the bore of the well pipe, as the anchoringdevice is moved upwardly through the well pipe. Such-mven1ent betweenthe expander portion surface and the dogs also tends to dislodge aredisposed in and adapted to move radially inwardly and outwardly oflongitudinally extending grooves 61 formed in the sealing and key member38. While two opposed key members are illustrated, it is to beunderstood that only a single key or more than two may be used, ifdesired.

The selector key members are normally biased outwardly of the slotstoward engagement with the bore wall of the well pipe and with thegrooves in the landing section by means of a resilient member or spring62 mounted in each slot and bearing against the bottom of the'slot andthe inner side of each adjacent selector key member. The resilientmembers may be a leaf spring, as shown, or may be coil springs, or thelike. The keys are retained against displacement from the slots at theirupper end by a retaining ring or band 63 mounted in a suitable externalannular groove formed in the periphery of the packing and key member 38,and at their lower ends are confined against displacement from the slotsby a thimble retaining member 64 threaded onto the lower end of theselector key body member. The threaded lower end of the selector keymember extends below the thimble retaining member 64, and a suitablewell flow control device or other well tool may be threaded onto thelower end of said member for controlling or restricting flow through thebore 39 of the carrier member.

Each of the selector key members has a plurality of bosses formedthereon and, as shown, preferably includes a lower guide boss 70, a stopboss 71 and an upper guide boss 72. The upper and lower guide bosses areprovided with outwardly convergent beveled surfaces at their upper andlower ends, whereby said bosses will cam the keys inwardly toward aretracted position upon encountering any obstruction or shoulder in thebore of the well pipe or in the landing section through which thecarrier passes. The stop boss 71 has formed thereon at its lower end anabrupt stop shoulder 75 disposed substantially normal to thelongitudinal axis of the carrier, and adapted to engage the upwardlyfacing stop shoulder 26 in the stop groove of the landing section forwhich the selector key is designed. Such engagement, as shown in'Figure3, provides a positive stop limiting further downward movementof thecarrier 35 through the well pipe and positioning or locating the lockingdogs 41 in position to be expanded into the locking groove 20 to preventupward movement ofthe carrier from the landing section.

The bosses on the outer face of the selector keys form what may becalled a selective stopping surface or key face, and the distance whichthe upper and lower guide bosses 70'and 72 project determines which ofthe landing sections the keys will engage in and cooperate with, sincethe depth of the upper and lower selective grooves 22 and 23,respectively, must conform substantially to the size of the upper andlower guide bosses 72 and 70, respectively, in order for the stop bosses71 to enter the stop groove 21 and permit the stop'shoulder 75 on suchkeys to engage the stop shoulder 26 in the stop groove. As is clearlyshown in Figure 5, when the selector key 60 passes through one of theupper landing sections 111, the lower guide boss 70' and the upper guideboss 72 will engage the outer or bottomsurface of the lower key groove123 and of the upper key groove 122, respectively, and so limit outwardmovement of the downwardly facing stop shoulder 75 on. the selector key,whereby said stop shoulder cannot engage the, upwardly facing stopshoulder 126 in the lock groove 121- of the landing sec tion-11 1. Thus,the anchoring device will passdownwardly through the landing section111', and through the bore of the well pipe, until' it enters thelandingsection 11 wherein the selector grooves 23 and 22 and the locking groove21 are of a configuration to conform substantially to the configurationof the bosses on the selector key 60. Upon entering the landing section11, the stop shoulder 75' on the selector key will engage the stopshoulder 26 in the stop groove and will limit further downward movementof the anchoring mechanism through the well pipe and position thelocking dogs 41in the proper position to be engaged in the lockinggroove 20 for preventing upward movement of the device out of thelanding section.

In use, the landing sections 11, 111 and 21 1, etc., are made up-in the.pipe string at the desired levels in which itis anticipated that theanch-oring'devicesshould be located during operation of the well. Thisisdone as the pipestring is made up and lowered into the well bore, andthe landing sections actually constitute a part of the pipe string orflow conductor.

Where a plurality of well tools or flow controls are to until the stopshoulder 75 onthe stop boss engages the upwardly facing stop shoulder26' in the stop groove in.

the landing section to arrest further downward movement of theanchoringdevice. In this position", shown in Figure 3, the locking dogs 41 arepositioned with the bosses 42 in the locking groove 20, but notnecessarily movedto fully expanded or locking position. In order toproperly lock the device in place in the landing section,.it ispreferable to shift the carrier upwardly on its longitudinal axis untilthe beveled upper ends of the bosses 42 engage the downwardly facingshoulder 24 at the upper end of the lock gro-ove'and the upwardly facingstop shoulder 47 at the lower end of the expander surface of theexpander member engages the lower ends of thev locking dogs. Inthisposition, the dogs are fully expanded and further undesired upwardmovement of the anchoring device is prevented.

The selector key or keys are always resiliently'biased outwardly by thesprings, and are therefore always ready to go into operation to engagethe stop shoulder 26 to arrest or limit downward-movement of theanchoringdevice. It will be understood that in normal circumstancesfluid pressure frombelow the anchoring'device acting across the sealingmeans 50 tends to hold the device upwardly in the locked position, butit is frequently desired to pump fluid downwardly into the well throughthe well pipe, and in such event the selector keys will engage the stopshoulder 26 to prevent unrestricted downward movement of the device atthat time and during such. downward pumping of fluids.

It will be noted that during the time that the anchoring device is inthe upper position with the locking dogs engaged with the shoulder 24 atthe upper end of the locking groove, the selector keys 60 are heldinwardlyin the retracted position substantially as shown in Figure 2,whereby sand or other detritus cannot accumulate be hind the keys toprevent retraction of the same. Thus, when it is desired to remove thedevice from within the well tubing, it. is assured that the selectorkeys will permit the carrier to be moved upwardly. Since theinternaldiameter of the landing section at the point-at which it is 7engaged by the upper guide boss 72 of the selector keys when inretracted position is intentionally made at least as small as anyinternal diameter in the bore of the well pipe above the landingsection, when the locking dogs are released the keys will not interferewith the removal'of the carrier from within the well pipe.

It is contemplated that the selector keys may be positioned on thecarrier in such a manner as to permit the upper guide boss 72 to engagein the locking groove 20. This would permit elimination of one of thegrooves in the landing section. In such case the locking dogs 41 wouldengage in the same groove with the upper guide boss 72, such lockingd-ogs being spaced circumferentially of the carrier from the selectorkeys so as not to interfere with each other. Furthermore, it iscontemplated that the carrier may be so constructed that the selectorkeys are not moved out of the several selector grooves or the selectorgroove portion of the landing section when the locking dogs are moved tofully expanded locking position. It is also contemplated that in somecases the upper guide boss 72 may be omitted from the selector keys andonly the lower guide boss 70 be used, in which event the beveled surfaceat the upper end of the stop boss 71 would engage any obstructions abovethe device and initially cam the selector key inwardly, the lower guideboss subsequently engaging such obstruction and further camming theselector key inwardly as the anchoring device is moved upwardly throughthe well pipe. In lowering an anchoring device having such a modifiedselector key, the lower guide boss would adequately prevent engagementof the stop shoulder 75 on the selector from engagement with the stopshoulder 26 of landing sections for which the selector key was notdesigned, the diameter of the boss being adequate to prevent engagementof the stop shoulders.

From the foregoing, it will be seen that this invention is well adaptedto attain all the ends and objects hereinbefore set forth, together withother advantages which are obvious and which are inherent to thestructure.

The foregoing description of the invention is explanatory only, andchanges in the details of the construction illustrated may be made bythose skilled in the art, within the scope of the appended claims,without departing from the spirit of the invention.

.What I claim and desire to secure by Letters Patent is:

1. As a sub-combination, a landing section adapted to be connected in awell string and having an internal recess formed therein, the surfacesof said section defining the upper and lower limits of said recess beingdivergent inwardly of said section, said section having an internalflange providing an upwardly facing abrupt stop shoulder formed in saidrecess intermediate said divergent surfaces and also having a secondannular tapered flange formed therein above said stop shoulder.

2. In combination, a landing section means adapted to be connected in apipe string, and anchoring tool means, one of said landing section meansand anchoring tool means having a resiliently biased selector key, theother of said landing section means and said anchoring tool means havinga lateral groove of lateral size and configuration corresponding to saidselector key, said key and said groove having co-engageable stop partsfor arresting downward movement of the anchoring tool means through saidlanding section means, locking means parts on each the landing sectionmeans and the anchoring tool means co-engageable tosecure the anchoringtool means against upward movement out of said landing section means andretractable from engagement to permit said anchoring tool means to beremoved upwardly from the landing section means, said groove havingdivergent beveled surfaces defining the upper and lower limits of saidgroove, said selector key having a pair of spaced projecting taperedbosses one above and one below said stop parts thereon, said taperedbosses providing beveled upward movement of said anchoring tool means toretract the key from said groove.

3. A device for releasably anchoring a well toolat a selected levelwithin a well pipe comprising: a carrier; locking means on said carrierexpandable and-retractable laterally thereof; means on said carriermovable to expand 3 said locking means; a selector member on saidcarrier movable laterally of said carrier; means biasing said selec- Itor member outwardly of said carrier, said selector member having a pairof spaced tapered bosses providing 0utwardly convergent surfaces at itsupper and lower ends and an outwardly extending abrupt stop shoulderintermediate said convergent surfaces; the lateral dimension of 1 thebosses of said selector member above and below said stop shoulder beinggreater than the lateral dimension of said stop shoulder.

4. A device for releasably anchoring a well tool at a selected level ina well pipe having a plurality of spaced tubular landing sectionsconnected therein at selected levels and each of said landing sectionshaving an internal positioning and locking surface having a plurality ofspaced annular grooves formed therein, the lower limit of one of saidgroves being defined by an upwardly facing stop shoulder, one of saidgrooves having upper and lower limits defined by divergently inwardlyextending shoulders, said positioning and locking surface of eachlanding section having at least one of the grooves formed therein of adifferent lateral dimension than the corresponding groove of the otherlanding sections, said device including: a carrier; locking dogs mountedon said carrier; expander means on said carrier for lateral expansion ofsaid dogs upon longitudinal movement of said means relative to saiddogs; and a selector member mounted on said carrier for limited lateralexpansion and retraction; means biasing said selector member outwardly;

said selector member having a key section having a downwardly facingstop shoulder engageable with the one of said grooves of a selected oneof said landing sections having said upwardly facing stop shoulder tostop downward movement of the carrier at said selected landing sectionand to position the locking dogs in position to engage with one of saidgrooves in said landing nipple whereby longitudinal movement of theexpander means relative to said dogs will expand the dogs to lockingengagement in said groove; said selector key member having a pair ofspaced outwardly tapered bosses thereon one above and one below thedownwardly facing stop shoulder, each of said bosses projectinglaterally a distance greater than the depth of the corresponding groovesof non-selected landing sections connected above said selected landingsection in the pipe, whereby the downward ly facing stop shoulder ofsaid selector key section will not enter the stop shoulder grooves ofsuch non-selected landing sections.

5. In combination, a well pipe havinga plurality of spaced landingsections connected therein at selected levels and each having aninternal positioning and locking surface having a plurality of spacedannular grooves formed therein, the lower limit of one of said groovesbeing defined'by an upwardly facing stop shoulder, one of said grooveshaving upper and lower limits defined by divergently inwardly extendingshoulders, said positioning and locking surface of each landing sectionhaving at least one of the grooves formed therein of a different lateraldepth than the corresponding groove of the other landing sections, and adevice for releasably anchoring a well tool in a selected one of saidlanding sections including: a carrier; selective locking means mountedon said carrier for limited lateral expansion and retraction and havinga downwardly facing stop shoulder, an upwardly facing lock shoulder anda surface below said lock sh0ulder inclined downwardly and outwardly ofthe longitudinal axis of the carrier and providing a selector keyportion on said selective locking means; means for moving said selectivelocking means to locking position; said selector key portion having alateral dimension engageable with the one of the grooves of a selectedone of said landing sections having the divergent inwardly extendingshoulders and the different lateral depth; the lateral dimension of saidselector key portion being greater than the depth of the correspondinggrooves of non-selected H landing sections connected above said selectedlanding section in the well pipe, whereby said selector key portion willnot permit the stop shoulder on the selective locking means to engagethe upwardly facing stop shoulders in the non-selected landing sectionsthereabove.

6. A device for releasably anchoring a well tool at a selected level ina well pipe having a plurality of spaced tubular landing sectionsconnected therein at selected levels and each of said landing sectionshaving an internal positioning and locking surface having a plurality ofspaced annular grooves formed therein, the lower limit of one of saidgrooves being defined by an upwardly facing stop shoulder, one of saidgrooves having upper and lower limits defined by divergently inwardlyextending shoulders and having a lateral depth differing from the depthof the corresponding groove of the other landing sections; said deviceincluding: a carrier; selective locking means on said carrier movablelaterally of said carrier; means for moving said selective locking meansto expanded position; said selective locking means having a downwardlyfacing stop shoulder formed thereon adapted to engage the upwardlyfacing stop shoulder of a selected one of said landing sections, andalso having a selector key portion disposed below the stop shoulder andhaving outwardly convergent surfaces, said selector key portion beingadapted to engage in the one of the grooves having a lateral dimensiongreater than the depth of the corresponding grooves of non-selectedlanding sections connected thereabove in the well pipe whereby saidselector key section will not enter the grooves of said non-selectedlanding sections, thus preventing the stop shoulder of the selectedlocking means from engaging the upwardly facing stop shoulders in thegrooves of the internal positioning and locking surfaces of thenon-selected landing sections.

7. A device for releasably anchoring a well tool at a selected level ina well pipe having a plurality of spaced tubular landing sectionsconnected therein at selected levels and each having an internalpositioning and locking surface having a plurality of spaced annulargrooves formed therein, the lower limit of one of said grooves beingdefined by an upwardly facing stop shoulder, one of said grooves havingupper and lower limits defined by divergently inwardly extendingshoulders, said positioning and locking surface of each landing sectionhaving at least one of the grooves therein other than the groovecontaining the stop shoulder formed with a different lateral depth thanthe corresponding groove of the other landing sections, said deviceincluding: a carrier; locking dogs mounted on the carrier; expandermeans on the carrier for movement of the dogs to locking position uponlongitudinal movement of the expander means rela- 10 tive to the dogs;and a selective stop member mounted on the carrier for limited lateralexpansion and retraction; means biasing said stop member outwardly; saidselective stop member having a downwardly facing stop shoulder formedthereon engageable in the one of said grooves of a selected one of saidlanding sections having the upwardly facing stop shoulder therein tostop downward movement of the carrier at said selected landing sectionand to position the locking dogs in position to engage in one of thegrooves of said landing section, whereby longitudinal movement of theexpander means relative to said dogs expands said dogs into lockingengagement in said groove;

said selective stop member having a selector key portion thereon adaptedto engage in the one of the grooves of the selected landing section,said selector key portion having a lateral dimension greater than thedepth of corresponding grooves in non-selected landing sectionsconnected above said selected landing section in the pipe, whereby thestop shoulder of said selective stop member is prevented from engagingthe upwardly facing stop shoulders of non-selected landing sections.

8. A device for releasably anchoring a well tool at a selected levelwithin a well pipe comprising: a carrier; locking means on said carrierexpandable and retractable laterally thereof; means on said carriermovable to expand said locking means; a selector member on said carriermovable laterally of said carrier; means biasing said selector memberoutwardly of said carrier; said selector member having outwardlyconvergent surfaces at its upper and lower ends and an outwardlyextending abrupt stop shoulder intermediate said convergent surfaces;said selector member also having a downwardly facing upwardly andoutwardly inclined shoulder above said stop shoulder and an upwardlyfacing downwardly and outwardly inclined shoulder below said stopshoulder, the lateral dimension of the selector member above saiddownwardly facing upwardly and outwardly inclined shoulder and belowsaid upwardly facing downwardly and outwardly inclined shoulder beinggreater than the lateral dimension of the selector member at the stopshoulder.

9. A device for releasably anchoring a well tool at a selected levelwithin a well pipe comprising: a carrier; locking means on said carrierexpandable and retractable laterally thereof; means on said carriermovable to expand said locking means; a selector member on said carriermovable laterally of said carrier; means biasing said selector memberoutwardly of said carrier; said se- 7 lector member having an abruptstop shoulder formed on its outer face intermediate its ends; saidselector member being provided with guide bosses above and below saidstop shoulder on the outer face of said selector member, said guidebosses each having outwardly convergent beveled upper and lower faces.

References Cited in the file of this patent UNITED STATES PATENTS

